1. Field of the Invention
This invention relates to methods and compositions for sorbing flammable liquids and rendering them non-hazardous.
Specific embodiments of this invention include sorbent compositions which readily soak up hydrocarbons and other flammable liquids and both immobilize the liquid and render it fire safe.
2. Description of the Related Art
Spills of fuels, oils, hydraulic fluids, solvents and other flammable liquids are common in the course of equipment maintenance procedures, refueling operations and accidents involving vehicle collisions or roll overs. A great variety of absorbent materials have been used to soak up such flammable liquids from the ground, from garage floors, roadways and the like. Commonly used absorbents for this purpose include both organic and inorganic materials. Useful organic absorbents include activated carbon, sawdust, wood pulp, paper, peanut hulls, shredded peat moss and similar cellulosic materials. Commonly used inorganic absorbents include clays, pumice, expanded micas, diatomaceous earth, fullers earth and many more. A patent to Ericsson, U.S. Pat. No. 4,537,877 effectively summarizes the state of the art and presents a comprehensive description of solid absorbents, both organic and inorganic, which are used to soak up organic liquids and sets out advantages and disadvantages of the various materials.
Small spills of flammable liquids, those from a few gallons to a few tens of gallons, have ordinarily been treated quite casually in the past. It has been common practice to simply wash down small spills with water in order to reduce the hazard of fire at an accident scene or at a refueling site. Spills on shop floors and maintenance facilities were often washed down drains and into the sewer system or were soaked up with an absorbent which was then discarded with solid waste to a land fill.
Environmental concerns and regulations have rendered many of those past practices unacceptable. In most instances the practice of washing hydrocarbon spills into sewers or surface waters has been severely restricted or totally prohibited. Land fill regulations now ordinarily prohibit placement of wastes which contain leachable hydrocarbon or solvent liquids. Consequently, there has developed an increasing reliance on solid absorbents to clean up those liquid spills.
Solid absorbent compositions available today have a lot of short comings when used to clean up spills of flammable liquids. Many organic absorbents have a relatively high absorption capacity for flammable liquids but such materials are ordinarily quite flammable themselves and, if finely powdered, can even present an explosion hazard during use. Such absorbents are, of course, highly flammable after soaking up a flammable liquid and consequently tend not to reduce the fire hazard during the cleanup procedure. Inorganic absorbents, although not being combustible, offer little if any improvement in fire safety over organic absorbents as the absorbed liquid is readily ignited. Typical inorganic absorbents do not have as large an absorption capacity as do their organic counterparts and tend not to strongly retain liquid but instead tend to allow the liquid to bleed from the absorbent. Both organic and inorganic absorbents, especially if in powder form, are messy and difficult to clean up after being applied to a spilled liquid.
The safety aspects of spilled flammable liquids are receiving increasing attention and concern. Such safety concerns have at least two dimensions. In one aspect, there is concern over the exposure to fumes and vapors received by workers or others in the proximity of the spill. In another aspect, there is increasing concern and increasing regulation directed to the hazards of explosion or fire presented by the spilled liquid. The regulatory climate is tending toward requiring that spills of flammable liquids be immediately treated so as to make remote the chance of explosion or fire. Such regulations generally require that the spill be treated in a manner that effectively increases the flash point to a level, typically 140.degree. F. (60.degree. C.), which is relatively safe from ignition. In the case of a spill of jet fuel on tarmac during the refueling of an airplane, for example, attainment of the required safe flash point level is ordinarily accomplished by spreading an absorbent clay or similar material on the liquid and then capping the spill area with foam. The absorbent containing the spilled fuel and the foam are then gathered up, usually by hand, and placed in containers for transport to a disposal facility. Because of the highly caustic nature and fluorocarbon polymer base of the foams typically used for this purpose, the entire collected mass, absorbent, fuel and foam, usually must be treated as hazardous waste thus greatly increasing the disposal cost.
With this background, it can readily be appreciated that an absorbent composition which has a high absorption capacity for flammable liquids, which is easy to clean up and remove after soaking up a spilled liquid, which can raise the flash point of the composition containing the spilled liquid to a safe level, and which is neither caustic nor toxic provides important advances in the art of art of spilled liquid control.